dt-bindings: rng: r200: Add interrupt property

This IP block has an interrupt. Add it and add it to the
example as well.

Acked-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Florian Fainelli <[e-mail]>

Documentation/devicetree/bindings/rng/brcm,iproc-rng200.yaml

···
   reg:
     maxItems: 1
 
+  interrupts:
+    maxItems: 1
+
 additionalProperties: false
 
 examples:
   - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
     rng@18032000 {
         compatible = "brcm,iproc-rng200";
         reg = <0x18032000 0x28>;
+        interrupts = <GIC_SPI 83 IRQ_TYPE_LEVEL_HIGH>;
     };